On Fri, Aug 29, 2025 at 12:07:59AM +0100, Al Viro wrote:
> Actual removal is done under the lock, but for checking if need to bother
> the lockless list_empty() is safe - either that namespace never had never
nit: two "never"s
> been added to mnt_ns_tree, in which case the list will stay empty, or
> whoever had allocated it has called mnt_ns_tree_add() and it has already
> run to completion. After that point list_empty() will become false and
> will remain false, no matter what we do with the neighbors in mnt_ns_list.
>
> Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
> ---
Reviewed-by: Christian Brauner <brauner@xxxxxxxxxx>
> fs/namespace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/namespace.c b/fs/namespace.c
> index c324800e770c..daa72292ea58 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -195,7 +195,7 @@ static void mnt_ns_release_rcu(struct rcu_head *rcu)
> static void mnt_ns_tree_remove(struct mnt_namespace *ns)
> {
> /* remove from global mount namespace list */
> - if (!is_anon_ns(ns)) {
> + if (!list_empty(&ns->mnt_ns_list)) {
> mnt_ns_tree_write_lock();
> rb_erase(&ns->mnt_ns_tree_node, &mnt_ns_tree);
> list_bidir_del_rcu(&ns->mnt_ns_list);
> --
> 2.47.2
>
